In the last two decades various engineered antibody derivatives, either mono or -multispecific, either mono- or multivalent have been developed and evaluated (see e.g. Holliger, P., et al., Nature Biotech 23 (2005) 1126-1136; Fischer N., and Léger O., Pathobiology 74 (2007) 3-14).
For certain antigens as e.g. c-Met monovalent antibodies have different properties such as lack of agonistic function or reduced receptor internalization upon antibody binding than their corresponding bivalent forms and therefore represent attractive formats for therapeutic use. E.g. WO 2005/063816 refers to monovalent antibody fragments as therapeutics.
US 2004/0033561 describes a method for the generation of monovalent antibodies based on the co-expression of a VH-CH1-CH2-CH3 antibody chain with a VL-CL-CH2-CH3 antibody chain; however, a disadvantage of this method is the formation of a binding inactive homodimer of VL-CL-CH2-CH3 chains as depicted in FIG. 2. Due the similar molecular weight such homodimeric by-products are the difficult to separate.
WO 2007/048037 also refers to monovalent antibodies based on the co-expression of a VH-CH1-CH2-CH3 antibody chain with a VL-CL-CH2-CH3 antibody chain, but having a tagging moiety attached to the heavy chain for easier purification of the heterodimer from the difficult-to-separate homodimeric by-product.
WO 2009/089004 describes another possibility to generate a heterodimeric monovalent antibody using electrostatic steering effects.
WO 2010/145792 relates tetravalent bispecific antibodies, wherein mismatched byproducts of similar weight are reduced resulting in higher yields of the desired bispecific antibody.